Influence of the first stage on the final pressure in a two-stage rotary pump

Abstract

The two-stage oil sealed rotary vane pumps generally consist of two pumps in series inside a common housing. The high vacuum pump compresses gases from the recipient into the intermediate volume. From here the gas is exhausted and additionally compressed by the low vacuum pump and released into the atmosphere. The pressure in the intermediate volume is limited by the oil vapour pressure and its degassing rate. In developing a two-stage oil sealed vacuum rotary pump we tried to state the interdependence of both pressures. The experimental pump arrangement which enables pressure adjustment and the results of measurements is described.